Plant-based biopolymers for wastewater pollutants mitigation

Abstract Pollution is one of the most pressing issues of modern times. Effluent in the world is escalating due to the exponential growth in the industrial and agricultural sectors. The effluents contain heavy metals, pesticides, and inorganic substances ultimately leading to the deterioration of the ecosystem. Even though there are numerous wastewater treatment methods like adsorption, membrane separation, ion exchange, and physical, mechanical, and chemical treatments. They are expensive and have the risk of second-hand pollution. Biopolymers are alternate and superior to synthetic polymers due to their environmentally friendly approach and high efficiency in treating wastewater. The most prominent plant-based biopolymers for the treatment of pollutants are cellulose, starch, carrageenan, alginate, xylan, inulin, pectin, and tragacanth. These have their advantages and disadvantages in bioremediation. The mechanism of pollution removal has adsorption, flocculation, bridge formation, and electrostatic patches. They are biodegradable as they are natural in origin. They have proved to remove toxic pollutants like chitosan, pullulan, polyhydroxy alkonates and butyrates, dextran, starch and cellulose, polyvinyl alcohol and polycaprolactone, gelatin, collagen and wheat gluten, alginate, heparin, and pectin to name a few. Biopolymers are also sourced from diverse sources like agricultural wastes and well-known sources like plants, animals, and microbes. Biopolymer and its composites are utilized as coagulants and flocculants. They are cellulose graft polyacrylamide, anionic sodium carboxymethylcellulose, guar gum graft polyacrylamide, pectin polyacrylamide, starch, and tannin. Nanotechnology has led to the development of elite nanohybrid bio-adsorbents to actively remove pollutants. These nano adsorbents have been targeting pollutants like azo dyes, bovine serum albumin, cationic dyes, parabens, and methylene blue among others. Biopolymer composites are also widely used for diverse applications primarily due to their enhanced mechanical and thermal properties. Biopolymers from natural and synthetic sources can be modified and used as per the requirement.